Wilder recorded the 40th knockout of his career just two minutes, 17 seconds into the fight at Barclays Center in New York.
Wilder (41-0-1) started well and capitalised, landing the decisive blow quickly against his rival and fellow American.
After a war of words in the build-up, Wilder showed his class in his first fight since drawing with Tyson Fury in December, his performance set to again lead to calls for a rematch with the Brit or fight with fellow heavyweight champion Anthony Joshua.
— SHOWTIME Boxing (@ShowtimeBoxing) May 19, 2019
"Everything just came out of me," he told Showtime.
"I know it's been a big build-up to this fight, there was a lot of animosity, a lot of chaos, a lot of hatred against each other.
"There were a lot of words that were said and it just came out."
Wilder made a fast start and he had Breazeale in trouble early after a big left hand, only for the latter to steady – albeit very briefly.
Just seconds later, the fight was over.
Wilder landed a left-handed jab before a huge right sent Breazeale to the canvas, ending the fight and marking a ninth successful title defence.
Photo Getty Images. Caption: American Deontay Wilder